Darkmaross how much did it cost you to replace the ECT? And what fuses did you pull or replace? I did the battery cable and it worked for 3 weeks with no issue but now it started up again. I'm getting pissed about it can someone point me in some what of a direction?

Only the ECT which I think it was $20-30 at a dealer. The fuse, I think it was the PCM fuse someone here mentioned. Same fuse you have to do for the octane and main spark correction; nothing major. I identified part of the problem when I tried to read the coolant temperature with my X4 and it wasn’t reading anything so it was quite obvious. I followed the fuse part as a recommendation as I had nothing to lose, but my problem and solution was the same thing I had to do with an old 3.8L V6 Firebird I had.

My experience is, along with what I mentioned, you will feel some hesitation while the engine runs as the PCM doesn’t know how much gas it needs to send when the engine is cold versus when it reaches operating temperature. Having an 160 thermostat had nothing to do with the issue, especially when I never changed the fan temperature setting on purpose, so the thermostat opens earlier but the engine is still allowed to go up in temperature before the fans kick off. Remember each setup is different, and I wasn’t running anything crazy that forced me to change the fan settings.

I had the same issue recently, I changed the engine temp sensor & it was ok for a while then came back, I changed my 160 thermostat to 178 checked coolant level & drove for less than an hour & it came back temperature here is 45C+ & my chiller is not doing its job with this issue .
Any other thing need to be done ?
Ahmad